Unvaccinated students could be asked to stay home from school amid a smoldering mumps outbreak in Ohio, health officials said.

The message comes one week before the start of the school year in Columbus, Ohio, where roughly 479 people have contracted mumps since March, according to Jose Rodriguez, a spokesman for Columbus Public Health.

The MMR vaccine is the best way to prevent mumps, according to the CDC, with two doses guarding 86 percent of kids from the disease. But some kids are excused from the shot, which is required by Ohio public schools, for religious or personal beliefs. In 2012, only 90 percent of the state's kids got one more or doses of the vaccine, according to CDC data -- down from 93 percent in 2011.

While most of the Ohio mumps cases have occurred in vaccinated people, health officials suspect that unvaccinated people are helping to spread the virus.

“We believe a few unvaccinated individuals put the whole community at risk,” Rodriguez said.

To help curb the outbreak, officials are asking unvaccinated kids to stay home from school for at least 25 days after a reported mumps case in their community. The 25-day period was chosen based on the incubation period of the virus, Rodriquez said.

“Some kids whose parents chose not to get them vaccinated at first have now vaccinated because of the outbreak and because of the risks,” he added. “That’s encouraging.”